Thousands of soccer fans stampeded outside a stadium in Tembisa, South Africa, on Sunday before an exhibition game between Nigeria and North Korea, leaving 15 people injured, including one police officer who was seriously hurt.

Several fans fell under the rush of people, many wearing Nigeria jerseys. The Makhulong Stadium in the Johannesburg suburb seats about 12,000 fans.

The mayhem happened only five days before the start of the World Cup, the first to be held in Africa.

"At this moment we have 14 civilians that were slightly injured in the process, one policeman seriously injured," police spokesman Lt. Col. Eugene Opperman said outside the stadium. The injured were being treated at a hospital, he said.

Opperman said tickets for the game were given out for free outside the stadium.

"What then occurred was large groups of people gathered outside the gates wanting to come in and wanting to get free tickets. Unfortunately in the process, the gates were opened and there was a stampede," Opperman said.

Soccer's international governing body said it had nothing to do with the ticketing.

"FIFA and the OC [local organizing committee] would like to reiterate that this friendly match has no relation whatsoever with the operational organization of the 2010 FIFA World Cup, for which we remain fully confident," FIFA said in a statement.

Police spokesman Col. Hangwani Mulaudzi added that because this was an exhibition game, the Nigerian team -- the designated host -- was responsible for security, not World Cup organizers.

Once trouble broke out, he said, police stepped in.

Official minimizes alert

The U.S. ambassador to South Africa played down the State Department's crime alert to Americans attending the World Cup. Ambassador Donald Gips, wearing a U.S. national team road jersey, attended the American training session.

"There is no new concern about violence," Gips said. "South Africa does have a crime problem that they're addressing, and we want to make sure Americans are aware of that and stay in places that are safe."

On May 27, the State Department cautioned U.S. citizens attending the World Cup to keep car doors and windows locked while driving and not to leave valuables in plain view or to wear expensive jewelry.

South Africa is ready

President Jacob Zuma declared South Africa ready for the start of the World Cup and praised the sporting event for bringing cohesion to his once divided nation.

Five days before kickoff, Zuma said the nation has not witnessed such enthusiasm and excitement since former president Nelson Mandela was released from an apartheid-era prison in 1990.

Zuma, who spoke to reporters at the presidential guesthouse in Pretoria with FIFA president Sepp Blatter at his side, applauded the explosion of national pride, saying it was a priceless benefit of the tournament.

Zuma also criticized those who doubted the nation's ability to host the first World Cup on the African continent.

"We knew from that moment that South Africa would never be the same. It is clear that millions of our people have waited for years and look upon this tournament with hope, pride and a sense of belonging," he said.

Beware the Americans

England midfielder Frank Lampard sees a dangerous opponent in the team's World Cup opener: the United States.

There is a growing awareness in the England camp that the Americans, who reached the Confederations Cup final in South Africa last June, will be tough in the Group C opener.

"They'll be very organized," Lampard said. "There is a certain rivalry considering the players they have who play in the Premier League. It'll be a tough game -- the first one always is."

Coach Fabio Capello was impressed by the United States' performance in a 2-1 defeat against the Netherlands in March.

"The quality of America is really good. They play a lot of passes -- it is the same style as Spain, they always create chances to score goals," Capello said.

Playing it safe

Brazil will be without goalkeeper Julio Cesar, who injured his back on Wednesday, when it faces Tanzania in its final warmup Monday before the World Cup, and Coach Dunga may rest other starters to protect them.